Press key device

Abstract

A press key device includes: a key cap, a base plate, a frame, and a restoring unit. The key cap includes a cap portion and a fin portion protruding from the cap portion. The base plate is disposed under the key cap and is formed with a first perforation which has opposite first and second ends in a first horizontal direction. The frame is disposed on the base plate and has a frame portion and a groove which has a limit groove portion. The frame is movable from a first position to a second position and further to a third position so that the fin portion is retained in the limit groove portion to restrain downward movement of the key cap.

What is claimed is: 
     
         1 . A press key device, comprising:
 a key cap including a cap portion and a fin portion protruding from said cap portion;   a base plate disposed under said key cap and formed with a first perforation which has opposite first and second ends in a first horizontal direction;   a frame disposed on said base plate and having
 a frame portion that is formed with a through hole for receiving said cap portion of said key cap, 
 a groove that is in spatial communication with said through hole, that is formed in a lower surface of said frame portion for receiving said fin portion of said key cap, and that has a main groove portion and a limit groove portion extending in the first horizontal direction from a top end of the main groove portion and having a width in a top-down direction smaller than that of said main groove portion, and 
 a first protrusion that protrudes from said lower surface of said frame portion and that is insertable into said first perforation, 
 wherein said frame is downwardly movable by a first distance together with said key cap with said fin portion of said key cap being retained in said top end of said main groove portion of said groove from a first position, where said frame is away from said base plate, to a second position, where said frame portion is in contact with said base plate and where said first protrusion is extended into said first perforation of said base plate, and 
 wherein said frame is further movable relative to said key cap in the first horizontal direction from the second position to a third position, where said first protrusion engages said second end of said first perforation and where said fin portion is retained in said limit groove portion so that downward movement of said key cap is restrained; and 
   a restoring unit disposed within said through hole of said frame and secured to said cap portion of said key cap for providing an upward restoring force to said key cap, said key cap being downwardly movable relative to said frame by a second distance longer than the first distance to make contact between said restoring unit and said base plate when said frame is at the first position.   
     
     
         2 . The press key device of  claim 1 , wherein said base plate is further formed with a second perforation having opposite first and second ends in the first horizontal direction, said frame further including a second protrusion that protrudes from said lower surface of said frame portion and that is insertable into said second perforation, said second protrusion being extended into said second perforation when said frame is at the second position, and engaging said second end of said second perforation when said frame is at the third position. 
     
     
         3 . The press key device of  claim 1 , wherein said first protrusion has a head portion and a stick portion extending from an end of said head portion in said first horizontal direction and having a maximum width in a second horizontal direction perpendicular to the first horizontal direction, said maximum width of said stick portion being smaller than that of said head portion, said first perforation of said base plate having a rounded hole part that has said second end of said first perforation, and an elongated hole part that is spatially communicated with said rounded hole part in said first horizontal direction, that has a maximum width in the second horizontal direction smaller than that of said rounded hole part, and that has said first end of said first perforation. 
     
     
         4 . The press key device of  claim 2 , wherein said first and second perforations of said base plate are spaced apart in said first horizontal direction. 
     
     
         5 . The press key device of  claim 2 , wherein said base plate includes a substrate, a membrane circuit layer disposed on said substrate, and an insulating layer disposed between said membrane circuit layer and said frame, said first and second perforations penetrating said substrate, said membrane circuit layer, and said insulating layer. 
     
     
         6 . The press key device of  claim 4 , wherein said base plate includes a substrate, a membrane circuit layer disposed on said substrate, and an insulating layer disposed between said membrane circuit layer and said frame, said first and second perforations penetrating said substrate, said membrane circuit layer, and said insulating layer. 
     
     
         7 . The press key device of  claim 1 , further comprising a scissors linkage interconnecting said key cap and said base plate and retractable when said keycap is downwardly moved.